Recently, STMicroelectronics released a new low-power family, STM32L4+, with extended performance (120MHz frequency) and up to 2MB dual bank flash memory and 640kB of RAM memory. Together with graphics support, it makes it the best ultra low-power device on the market for smart watches and other long life-high performance projects.
Benchmark result is 150DMIPS or 409 coremarks in ULPbench test by EEMBC.
STM32L4+ family consists of 3 main derivarions each with optional encryption.
You can find 3 different lines, each with or w/o encryption. All devices have 640kB of RAM and either 1MB or 2MB of flash. Line STM32Lx5 is suitable for high-performance and ultra low-power tasks where graphics support is not required, STM32L4x7 embeds Chrom-GRC and TFT LCD display interface, while STM32L4x9 adds additional MIPI-DSI interface for serial displays.
If you are already familiar with STM32 development, STM32L4+ is pin-to-pin compatible with previous STM32 families making it easy to port or upgrade from existing STM32L4 family.
Different ULP modes are available, depends on end user application and wakeup source support. Below are listed some benchmarks.
- Ultra‐low‐power mode: 20 nA with backup registers without real‐time clock (5 wakeup pins)
- Ultra‐low‐power mode + RTC: 200 nA with backup registers (5 wakeup pins)
- Ultra‐low‐power mode + 64 Kbytes of RAM: 800 nA
- Ultra‐low‐power mode + 64 Kbytes of RAM + RTC: 1μA
- Dynamic run mode: down to 43 μA/MHz
- Wake‐up time: 5 μs
Chrom-GRC is very similar to more known Chrom-ART (DMA2D) peripheral on other microcontrollers, but it is optimized for rounded displays, which helps you to optimize RAM usage by removing corners from memory.
Quad-SPI support has been extended to Octo-SPI, allowing you to transfer your favorite images for graphics with twice speed comparing to previous Quad-SPI features.
ADC is 12-bit with true hardware oversampling support up to 16-bits. To make effective 16-bits, sampling rate has been increased to 5MSPS.
From ecosystem point of view, STM32CubeL4 has been extended to version 1.10 to support newer devices in the same family. Keil, IAR and SW4STM32 support has been added for ST’s latest MCU support.
There are ready to use Nucleo, Discovery and EVAL boards for fast development startup and easy-to-use prototyping. They are available on your favorite reseller.
- Nucleo STM32L4R5 includes 144-pin version of microcontroller with 2MB flash and 640kB of RAM. Board has all the pins available on pin-headers making it very easy to start with prototyping and development. ST-LinkV2.1 includes debugger, Virtual COM port and mass storage device at the same time.
- Discovery STM32L4R9 uses most performance version of STM32L4+. There is 390×390 rounded display to test Chrom-GRC peripheral and internal SRAM as display buffer.
- EVAL STM32L4R9 embeds everything to test all the peripherals in microcontroller.
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